In situ and tunable deposition of a film

ABSTRACT

A method is provided. The method includes the following steps: introducing a first physical vapor deposition (PVD) target and a second PVD target in a PVD system, the first PVD target containing a boron-containing cobalt iron alloy (FeCoB) with an initial boron concentration, and the second PVD target containing boron; determining parameters of the PVD system based on a target boron concentration larger than the initial boron concentration; and depositing a FeCoB film on a substrate according to the parameters of the PVD system.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 17/581,958, filed Jan. 23, 2022, which claimspriority to U.S. Provisional Patent Application No. 63/227,999, filed onJul. 30, 2021, and entitled “APPARATUS AND METHOD FOR PHYSICAL VAPORDEPOSITION,” the entire disclosure of which is incorporated herein byreference.

FIELD

Embodiments of the present disclosure relate generally to physical vapordeposition (PVD), and more particularly to in situ and tunabledeposition of a film using a PVD system.

BACKGROUND

The semiconductor industry has experienced rapid growth due to ongoingimprovements in the integration density of a variety of electroniccomponents (e.g., transistors, diodes, resistors, capacitors, etc.). Forthe most part, improvement in integration density has resulted fromiterative reduction of minimum feature size, which allows morecomponents to be integrated into a given area.

While some integrated device manufacturers (IDMs) design and manufactureintegrated circuits (IC) themselves, fabless semiconductor companiesoutsource semiconductor fabrication to semiconductor fabrication plantsor foundries. Semiconductor fabrication consists of a series ofprocesses in which a device structure is manufactured by applying aseries of layers onto a substrate. This involves the deposition andremoval of various thin film layers. The areas of the thin film that areto be deposited or removed are controlled through photolithography. Eachdeposition and removal process is generally followed by cleaning as wellas inspection steps. Therefore, both IDMs and foundries rely on numeroussemiconductor equipment and semiconductor fabrication materials, oftenprovided by vendors. There is always a need for customizing or improvingthose semiconductor equipment and semiconductor fabrication materials,which results in more flexibility, reliability, and cost-effectiveness.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a schematic diagram illustrating an example PVD system inaccordance with some embodiments.

FIG. 2 is a bottom view of the lid of FIG. 1 in accordance with someembodiments.

FIG. 3 is a perspective view of PVD targets in accordance with someembodiments.

FIGS. 4A-4C are schematic diagrams illustrating the formation of FeCoBfilms with different boron concentration in accordance with someembodiments.

FIG. 5 is a flowchart illustrating an example method for forming a FeCoBfilm on a substrate in accordance with some embodiments.

FIG. 6 is a flowchart illustrating an example method for dynamicallytuning the boron concentration in accordance with some embodiments.

FIG. 7A is a diagram illustrating two PVD targets that are used for insitu and tunable deposition of a film on a substrate in accordance withsome embodiments.

FIG. 7B is a diagram illustrating two PVD targets that are used for insitu and tunable deposition of a film on a substrate in accordance withsome embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the subject matterprovided. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Some embodiments of the disclosure are described. Additional operationscan be provided before, during, and/or after the stages described inthese embodiments. Some of the stages that are described can be replacedor eliminated for different embodiments. Some of the features describedbelow can be replaced or eliminated and additional features can be addedfor different embodiments. Although some embodiments are discussed withoperations performed in a particular order, these operations may beperformed in another logical order.

Physical vapor deposition (PVD) is a common process for depositing afilm of material on a substrate and is commonly used in semiconductorfabrication. The PVD process is carried out at a high vacuum in achamber containing a substrate (e.g., a wafer) and a solid source orslab of the material (i.e., a “PVD target” or a “target”) to bedeposited on the substrate. In the PVD process, the PVD target isphysically converted from a solid into a vapor. The vapor of the targetmaterial is transported from the PVD target to the substrate, where itis condensed on the substrate as a film.

There are many methods for accomplishing PVD, including evaporation,e-beam evaporation, plasma spray deposition, and sputtering. Among thosemethods, sputtering is usually the most frequently used method foraccomplishing PVD. During sputtering, gas plasma is created in thechamber and directed to the PVD target. The plasma physically dislodgesor erodes (sputters) atoms or molecules from the reaction surface of thePVD target into a vapor of the target material, as a result of acollision with high-energy particles (ions) of the plasma. The vapor ofsputtered atoms or molecules of the target material is transported tothe substrate through a region of reduced pressure and condenses on thesubstrate, forming the film of the target material.

Some PVD targets contain more than one element. One example is an alloyof iron (Fe), cobalt (Co), and boron (B), which is sometimes alsoreferred to as a boron-containing cobalt iron alloy (FeCoB). FeCoB issometimes represented as Fe_(x)Co_(y)B_(z), where x, y, z are atomicpercentages of iron, cobalt, and boron, respectively, and x+y+z=100%.FeCoB is, for example, widely used in magnetic tunnel junction (MTJ),which is a building block of magnetoresistive random-access memory(MRAM) devices. In one example, a MTJ has a reference layer, a freelayer, and a tunnel barrier layer between the free layer and the pinnedlayer, and the reference layer, the tunnel barrier layer, and the freelayer are made of FeCoB, MgO, and FeCoB, respectively.

Some commonly used boron concentrations of FeCoB are 20%, 30%, 40%, and50%, corresponding to FeCoB₂₀%, FeCoB₃₀%, FeCoB₄₀%, and FeCoB₅₀%,respectively. FeCoB has different phases as the boron concentrationincreases. When the boron concentration is relatively low (e.g.,FeCoB₂₀%, FeCoB₃₀%, etc.), the FeCoB has a phase (Fe,Co)₂B; when theboron concentration increases (e.g., FeCoB₅₀%), the FeCoB has a phase(Fe,Co)B. There is a transition phase between those two situations,where those two phases (Fe,Co)₂B and (Fe,Co)B are coexisting. FeCoB₄₀%happens to be within this transition phase. As a result, FeCoB₄₀% PVDtargets are not as stable as other FeCoB PVD targets, such as FeCoB₂₀%PVD targets, and they are easy to crack. Additionally, FeCoB PVD targetsare usually provided by vendors, and the long-distance transportationfrom vendors to foundries and IDMs makes FeCoB₄₀% PVD targets even morevulnerable. The cracked FeCoB₄₀% PVD targets result in deterioratedparticle performances of the films deposited based thereon. It should beunderstood that although FeCoB PVD targets are used as an example, theabove-identified issues may exist in other PVD targets as well. Last butnot least, each of those commonly used FeCoB PVD targets has a fixedboron concentration such as 20%, 30%, 40%, and 50%. The boronconcentration is discrete (i.e., not continuous). This leads todifficulties when a specific boron concentration that is not commonlyused (e.g., 27.5%) is desired.

In accordance with some aspects of the disclosure, methods fordepositing a film on a substrate and corresponding simultaneously-usedPVD targets are provided. A pair of PVD targets are both exposed at thesame time (i.e., simultaneously) during the deposition of a FeCoB film.One is a FeCoB₂₀% PVD target, and the other is a boron PVD target. Bychoosing different PVD parameters, different boron concentrations of theFeCoB film deposited on the substrate can be achieved. The boronconcentration can vary continuously, as desired. In other words, theboron concentration can be tuned by using the FeCoB₂₀% PVD target andthe boron PVD target at the same time. The PVD parameters that can beused to tune the boron concentration of the film include one or more ofthe following parameters: the voltages applied to the PVD targets; thedeposition duration; the concentration of the plasma-forming gas such asargon (Ar). The in situ and tunable deposition of the FeCoB film offersmore flexibility and reduces the risk of cracked FeCoB₄₀% PVD targets.

FIG. 1 is a schematic diagram illustrating an example PVD system 100 inaccordance with some embodiments. The PVD system 100 is capable ofdepositing a film onto a substrate 102 using one or more PVD targets104. During the PVD process, the one or more PVD targets 104 arebombarded by energetic ions, such as plasma, causing material to beknocked off the one or more PVD targets 104 and deposited as a film onthe substrate 102. In the example shown in FIG. 2 , there are two PVDtargets 104. It should be understood that more than two PVD targets canbe used, which is within the scope of the disclosure.

In some embodiments, the PVD system 100 is a magnetron PVD systemincluding a chamber body 112, which encloses a processing region or aplasma zone 114. A substrate support 120 is disposed within the chamberbody 112. The substrate support 120 has a substrate receiving surface122 that receives and supports the substrate 102 during the PVD process,so that a surface of the substrate 102 is opposite to the front surfaces222 of the one or more PVD targets 104 that are exposed to theprocessing region 114. The one or more PVD targets 104 are disposed on alid 101. The substrate support 120 is electrically conductive and iscoupled to ground (GND) so as to define an electrical field between theone or more PVD targets 104 and the substrate 102. In some embodiments,the substrate support 120 is composed of aluminum, stainless steel, orceramic material. In some embodiments, the substrate support 120 is anelectrostatic chuck that includes a dielectric material.

A shield 130, also referred to as a “dark space shield,” is positionedinside the PVD chamber body 112 and proximate sidewalls 205 of the oneor more PVD targets 104 to protect inner surfaces of the chamber body112 and sidewalls 205 of the one or more PVD targets 104 from unintendeddeposition. The shield 130 is positioned very close to the targetsidewall 205 to minimize re-sputtered material from being depositedthereon. The shield 130 has a plurality of apertures (not shown) definedtherethrough for admitting a plasma-forming gas such as argon (Ar) fromthe exterior of the shield 130 into its interior.

A power supply 140 is electrically coupled to the backing plates 210 ofthe one or more PVD targets 104 through the lid 101. The backing plates210 are attached to the target plates 220, which contain differentsource materials of the PVD targets 104. The power supply 140 isconfigured to negatively bias the one or more PVD targets 104 withrespect to the chamber body 112 to excite a plasma-forming gas, forexample, argon (Ar), into a plasma. In some embodiments, the powersupply 140 is a direct current (DC) power supply source. In otherembodiments, the power supply 140 is a radio frequency (RF) power supplysource.

A magnet assembly 150 is disposed above the one or more PVD targets 104.The magnet assembly 150 is configured to project a magnetic fieldparallel to the front surfaces 222 of the one or more PVD targets 104 totrap electrons, thereby increasing the density of the plasma andincreasing the sputtering rate. In some embodiments, the magnet assembly150 is configured to scan about the back of the one or more PVD targets104 to improve the uniformity of deposition. In some embodiments, themagnet assembly 150 includes a single magnet disposed above the one ormore PVD targets 104. In some embodiments, the magnet assembly 150includes an array of magnets. In some embodiments and as shown in FIG. 1, the magnet assembly 150 includes a pair of back magnets 152 disposedabove the one or more PVD target 104. In some embodiments and as shownin FIG. 1 , the magnet assembly 150 also includes a side electromagnet154 around the chamber body 112.

A gas source 160 is in fluidic combination with the chamber body 112 viaa gas supply pipe 164. The gas source 160 is configured to supply aplasma-forming gas to the process region 114 via the gas supply pipe.The plasm-forming gas is an inert gas and does not react with thematerials in the one or more PVD targets 104. In some embodiments, theplasma-forming gas includes argon (Ar), xenon (Xe), neon (Ne), or helium(He), which is capable of energetically impinging upon and sputteringsource material (and the dopant in some embodiments) from the one ormore PVD targets 104. In some embodiments, the gas source 160 is alsoconfigured to supply a reactive gas into the PVD system 100. Thereactive gas includes one or more of an oxygen-containing gas, anitrogen-containing gas, a methane-containing gas, that is capable ofreacting with the sputtering source material in the one or more PVDtargets 104 to form a layer on the substrate 102.

A vacuum device 170 is in fluidic communication with the PVD system 100via an exhaust pipe 174. The vacuum device 170 is used to create avacuum environment in the PVD system 100 during the PVD process. In someembodiments, the PVD system 100 has a pressure in a range from about 1mTorr to about 10 Torr. The spent process gases and byproducts areexhausted from the PVD system 100 through the exhaust pipe 174.

FIG. 2 is a bottom view of the lid 101 of FIG. 1 in accordance with someembodiments. FIG. 3 is a perspective view of PVD targets in accordancewith some embodiments. In the example shown in FIG. 2 , the lid 101 hasfour recesses 282. Four PVD targets 104-1, 104-2, 104-3, and 104-4 arelocated in the four recesses 282, respectively. In the example shown inFIG. 2 , the PVD target 104-1 is a FeCoB₂₀% target, the PVD target 104-2is a boron (B) target, the PVD target 104-3 is a PVD target thatcontains material A, and the PVD target 104-4 is a PVD target thatcontains material B. It should be understood that although there arefour PVD targets 104-1, 104-2, 104-3, and 104-4 in the example shown inFIG. 2 , this is not intended to be limiting. In another example, thelid 101 has two recesses 282 that accommodate the PVD target 104-1 (aFeCoB₂₀% target) and the PVD target 104-2 (a boron target).

In the example shown in FIG. 2 , the PVD target 104-3 is covered by ashutter 284-1, and the PVD target 104-4 is covered by a shutter 284-2.The shutters 284-1 and 284-2 can be controlled to cover or expose thecorresponding PVD targets 104-3 and 104-4, respectively. As such, threetargets (e.g., the PVD targets 104-1, 104-2, 104-3) or four targets(e.g., the PVD targets 104-1, 104-2, 104-3, 104-4) can be exposed andused in the deposition of the film on the substrate 102.

Now referring to FIG. 3 , the PVD targets 104-1, 104-2, 104-3, and 104-4are formed in a circular shape. It should be noted that this is notintended to be limiting, and PVD targets with other shapes such assquare, rectangular, oval, triangular, and the like may be used. Asexplained above, each PVD target has a backing plate 210 and a targetplate 220.

The backing plate 210 is composed of or made from a conductive material,such as copper, copper alloys, zinc, copper-zinc alloys, steel,stainless steel, iron, nickel, chromium, copper-chromium alloys,aluminum, lead, silicon, alloys thereof, derivatives thereof, orcombinations thereof. In some embodiments, the backing plate 210contains copper or a copper alloy. In some embodiments, the backingplate 210 includes a copper alloy having a copper concentration in arange from about 50% by weight to about 99.9% by weight, such as fromabout 55% by weight to about 95% by weight. In some other embodiments,the backing plate 210 includes a copper alloy having a copperconcentration in a range from about 50% by weight to about 70% byweight. In some embodiments, the backing plate 210 includes acopper-zinc alloy. In some embodiments, the copper-zinc alloy has acopper concentration in a range from about 58% by weight to about 62% byweight and a zinc concentration in a range from about 38% by weight toabout 42% by weight. In a specific example, the copper-zinc alloy of thebacking plate 210 contains about 60.8% copper by weight and about 39.3%zinc by weight. In other embodiments, the copper-zinc alloy has a copperconcentration in a range from about 75% by weight to about 85% by weightand a zinc concentration in a range from about 15% by weight to about25% by weight. In one specific example, the copper-zinc alloy of thebacking plate 210 contains about 80% copper by weight and about 20% zincby weight. In some embodiments, the backing plate 210 includes acopper-chromium alloy having a copper concentration in a range fromabout 95% by weight to about 99.5% by weight and a chromiumconcentration in a range from about 0.5% by weight to about 5% byweight. In a specific example, the copper-chromium alloy of the backingplate 210 contains about 99% copper by weight and about 1% chromium byweight.

As explained above, each target plate 220 has a front surface 222 thatis sputtered during the PVD process. The materials in the target plate220 are, thus, deposited onto the substrate 102 shown in FIG. 1 . Insome embodiments, the front surface 222 of the target plate 220 issubstantially flat. In some embodiments, the front surface 222 of thetarget plate 220 is curved. The target plate 220 contains correspondingsource material. For instance, the target plate 220 of the PVD target104-1 contains FeCoB₂₀%; the target plate 220 of the PVD target 104-2contains boron; the target plate 220 of the PVD target 104-3 containsmaterial A; the target plate 220 of the PVD target 104-4 containsmaterial B. In some embodiments, each target plate 220 further includesa dopant. The dopant affects the deposition rate of the sputteringsource material, which in turn changes the PVD process window andimproves wafer acceptance testing (WAT) yield.

As shown in FIG. 3 , the PVD targets 104-1 and 104-2 are usedsimultaneously in the PVD system 100 for depositing a FeCoB film on thesubstrate 102. Both the PVD targets 104-1 and 104-2 are exposed at thesame time (i.e., simultaneously). In conventional practice, FeCoB PVDtargets with fixed boron concentrations are used. The boronconcentration is discrete and cannot be tuned in situ. For example, aFeCoB₂₀% PVD target is used. If the boron concentration is lower thanexpected, the next boron concentration commonly available is 30%. Thereis no other boron concentration options between those two boronconcentrations (i.e., 20% and 30%). This significantly limits theflexibility of PVD processes. Moreover, FeCoB₄₀% PVD targets areunstable and easy to crack. The long-distance transportation fromvendors to foundries and IDMs makes FeCoB₄₀% PVD targets even morevulnerable.

In contrast, in accordance with embodiments of this disclosure, aFeCoB₂₀% PVD target 104-1 and a boron PVD target 104-2 aresimultaneously exposed and used. In one example, the boron PVD target104-2 has a high purity level, such as a purity level of about 99.999%(5N) or greater. The purity level is indicative of the source materialconcentration relative to the centration of impurities (other than thedopant that is intentionally introduced in some embodiments). In anotherexample, the boron PVD target 104-2 has a high purity level of about99.99% (4N) or greater. In yet another example, the boron PVD target104-2 has a high purity level of about 99.9% (3N) or greater. Bychoosing different PVD parameters, different boron concentrations of theFeCoB film deposited on the substrate 102 can be achieved. The boronconcentration can vary continuously, as desired. In other words, theboron concentration can be tuned by using the FeCoB₂₀% PVD target 104-1and a boron PVD target 104-2 together. The PVD parameters that can beused to tune the boron concentration of the film include one or more ofthe following parameters: the voltages applied to the PVD targets; thedeposition duration; the concentration of the plasma-forming gas such asargon (Ar).

FIGS. 4A-4C are schematic diagrams illustrating the formation of FeCoBfilms with different boron concentrations in accordance with someembodiments. In the example shown in FIG. 4A, source materials from theFeCoB₂₀% PVD target 104-1 and source materials from the boron PVD target104-2 are deposited on the substrate 102, and a FeCoB₃₀% film 402 a isformed on the substrate 102 as a result. In the example shown in FIG.4B, source materials from the FeCoB₂₀% PVD target 104-1 and sourcematerials from the boron PVD target 104-2 (more as compared to theexample shown in FIG. 4A) are deposited on the substrate 102, and aFeCoB₄₀% film 402 b is formed on the substrate 102 as a result. In theexample shown in FIG. 4C, source materials from the FeCoB₂₀% PVD target104-1 and source materials from the boron PVD target 104-2 (more ascompared to the example shown in FIG. 4B) are deposited on the substrate102, and a FeCoB₅₀% film 402 c is formed on the substrate 102 as aresult. Therefore, those commonly used boron concentrations (e.g., 30%,40%, and 50%) can be achieved in situ. The FeCoB₄₀% PVD target, which iseasy to crack, especially during the transportation from vendors to IDMsand foundries, can be avoided and replaced by the more stable FeCoB₂₀%PVD target and the boron PVD target.

It should be understood that the boron concentration of 20% can also beachieved by not using the boron PVD target. In some implementations, theboron PVD target 104-2 shown in FIG. 3 is covered by another shutter. Inother implementations, the boron PVD target 104-2 is removed temporarilyfrom the PVD system 100. It should also be understood that although onlythree example boron concentrations (i.e., 30%, 40%, and 50%) areillustrated in FIGS. 4A-4C, other boron concentrations can be achievedas well. As explained above, by varying the PVD parameters, the boronconcentration can be tuned and can vary continuously, as desired.

The boron concentration can vary continuously, as desired. In otherwords, the boron concentration can be tuned by using the FeCoB₂₀% PVDtarget 104-1 and a boron PVD target 104-2 together. The PVD parametersthat can be used to tune the boron concentration of the film include oneor more of the following parameters: the voltages applied to the PVDtargets; the deposition duration; the concentration of theplasma-forming gas such as argon (Ar).

FIG. 5 is a flowchart illustrating an example method 500 for forming aFeCoB film on a substrate in accordance with some embodiments. In theexample shown in FIG. 5 , the method 500 includes operations 502, 504,and 506. Additional operations may be performed. Also, it should beunderstood that the sequence of the various operations discussed abovewith reference to FIG. 5 is provided for illustrative purposes, and assuch, other embodiments may utilize different sequences. These varioussequences of operations are to be included within the scope ofembodiments.

At operation 502, a FeCoB₂₀% PVD target and a boron PVD target areintroduced in a PVD system. In one example, the FeCoB₂₀% PVD target isthe PVD target 104-1 shown in FIG. 2 , the boron PVD target is the PVDtarget 104-2 shown in FIG. 2 , and the FeCoB₂₀% PVD target and the boronPVD target are introduced in recesses 282 of the lid 101 of the PVDsystem 100 shown in FIGS. 1-2 .

At operation 504, parameters of the PVD system are determined based on atarget boron concentration. In one example, the target boronconcentration is 30%. In another example, the target boron concentrationis 40%. In yet another example, the target boron concentration is 50%.Once the target boron concentration is known, parameters of the PVDsystem, for example, the PVD system 100 shown in FIG. 1 , can bedetermined based on a target boron concentration, as explained above.

At operation 506, a FeCoB film is deposited on a substrate according tothe parameters of the PVD system. In one example, the PVD system shownin FIG. 1 operates, according to the parameters determined at operation504, to deposit a film on the substrate.

It should be understood that although the method 500 shown in FIG. 5 isused for depositing a FeCoB film on a substrate, similar methods can beapplied to the in situ and tunable deposition of other films on asubstrate. Those similar methods will be described below with referenceto FIGS. 7A and 7B. It should also be noted that other materials can beadded to the FeCoB film using the method 500. In one implementation,this can be achieved by using one or more PVD targets (e.g., the PVDtargets 104-3 and 104-4) in addition to the FeCoB₂₀% PVD target and theboron PVD target.

FIG. 6 is a flowchart illustrating an example method 600 for dynamicallytuning the boron concentration in accordance with some embodiments. Inthe example shown in FIG. 6 , the method 600 includes operations 602,604, 608, and 610. Additional operations may be performed. Also, itshould be understood that the sequence of the various operationsdiscussed above with reference to FIG. 6 is provided for illustrativepurposes, and as such, other embodiments may utilize differentsequences. These various sequences of operations are to be includedwithin the scope of embodiments.

At operation 602, a FeCoB film is deposited on a substrate using aFeCoB₂₀% PVD target and a boron PVD target. In one implementation,operation 602 can be fulfilled by method 500. In other words, a FeCoB₂₀%PVD target and a boron PVD target are introduced in a PVD system, andparameters of the PVD system are determined based on a target boronconcentration, and then a FeCoB film is deposited on the substrateaccording to the parameters of the PVD system.

At operation 604, the boron concentration of the film is monitored. Inone implementation, the boron concentration of the film is monitored byusing X-ray photoelectron spectroscopy (XPS). XPS is a surface-sensitivequantitative spectroscopic technique based on photoelectric effect thatcan identify the elements that exist within the film as well as theirchemical states. Because the energy of an X-ray with a particularwavelength is known, and because the emitted electrons' kinetic energiesare measured, the electron binding energy of each of the emittedelectrons can be determined by using the photoelectric effect equation.It should be understood that this is not intended to be limiting, andother techniques can be used to monitor the boron concentration of thefilm.

At operation 606, it is determined whether the difference between theboron concentration and the target boron concentration is below athreshold. In one example, the target boron concentration is 40%, andthe threshold is a predetermined value such as 1%, then the differenceis below the threshold when the boron concentration is higher than 39%but lower than 41%. The threshold can be set based on factors such asthe design variance tolerance.

If the difference between the boron concentration and the target boronconcentration is below the threshold, the method 600 proceeds tooperation 604, where the boron concentration of the film is monitored.In other words, the boron concentration of the film 604 may be monitoredrepeatedly. In one example, the boron concentration of the film isdynamically monitored until the deposition is completed.

If the difference between the boron concentration and the target boronconcentration is equal to or greater than the threshold, the method 600proceeds to operation 608, where the PVD parameters are adjusted basedon the difference. Then, the method proceeds to operation 602 again,where the FeCoB film is deposited on the substrate using the FeCoB₂₀%PVD target and the boron PVD target, based on the adjusted PVDparameters. The boron concentration of the film 604 is monitored againat operation 604. By adjusting the PVD parameters, the differencebetween the boron concentration and the target boron concentration canbecome below the threshold. As such, the boron concentration of the filmis adjusted to ensure that the difference between the boronconcentration and the target boron concentration is below the threshold.

As mentioned above, the method 500 can be applied to the in situ andtunable deposition of other films on a substrate. FIG. 7A is a diagramillustrating two PVD targets that are used for in situ and tunabledeposition of a film on a substrate in accordance with some embodiments.FIG. 7B is a diagram illustrating two PVD targets that are used for insitu and tunable deposition of a film on a substrate in accordance withsome embodiments.

In the example shown in FIG. 7A, a PVD target 704-1 contains an alloy ofthree elements A, B, and C. The alloy can be represented as ABC_(x1),where x1 is the atomic percentage of element C. On the other hand, a PVDtarget 704-2 contains element C. A method similar to method 500 shown inFIG. 5 can be used to deposit a film of the alloy of elements A, B, andC, and the deposition of the film is in situ and tunable, with theconcentration of element C higher than x1. In one example, x1 is 20%,and the concentration of element C in the film is 30%. In anotherexample, x1 is 10%, and the concentration of element C in the film is45%. In yet another example, x1 is 5%, and the concentration of elementC in the film is 7%. It should be understood that these examples are notintended to be limiting.

In the example shown in FIG. 7B, a PVD target 704-3 contains an alloy oftwo elements D and E. The alloy can be represented as DE_(x2), where x2is the atomic percentage of element D. On the other hand, a PVD target704-4 contains element E. A method similar to method 500 shown in FIG. 5can be used to deposit a film of the alloy of elements D and E, and thedeposition of the film is in situ and tunable, with the concentration ofelement E higher than x2. In one example, x2 is 20%, and theconcentration of element E in the film is 30%. In another example, x2 is10%, and the concentration of element E in the film is 45%. In yetanother example, x2 is 5%, and the concentration of element E in thefilm is 7%. It should be understood that these examples are not intendedto be limiting.

As illustrated in the examples shown in FIGS. 7A and 7B, the methodologydescribed above with reference to FIGS. 1-6 is generally applicable tothe deposition of a film using PVD targets that contain variousmaterials. In one example, the PVD target 704-3 shown in FIG. 7Bcontains titanium aluminide (TiAl), and the atomic percentage of Al is50% (i.e., Ti₅₀% Al₅₀%). By providing the PVD target 704-4 shown in FIG.7B, which contains Al, the deposition of a film of TiAl is in situ andtunable, with the concentration of Al higher than 50%.

In accordance with some aspects of the disclosure, a method is provided.The method includes the following steps: introducing a first PVD targetand a second PVD target in a PVD system, the first PVD target containinga boron-containing cobalt iron alloy (FeCoB) with an initial boronconcentration, and the second PVD target containing boron; determiningparameters of the PVD system based on a target boron concentrationlarger than the initial boron concentration; and depositing a FeCoB filmon a substrate according to the parameters of the PVD system.

In accordance with some aspects of the disclosure, a pair of PVD targetsare provided. The pair of PVD targets include a first PVD targetcontaining a boron-containing cobalt iron alloy (FeCoB) and a second PVDtarget containing boron. The first PVD target and the second PVD targetare used simultaneously in a PVD system for depositing a FeCoB film on asubstrate.

In accordance with some aspects of the disclosure, a method is provided.The method includes the following steps: introducing a first PVD targetand a second PVD target in a PVD system, the first PVD target containingan alloy of a first element, a second element, and a third element withan initial concentration of the third element, and the second PVD targetcontaining the third element; determining parameters of the PVD systembased on a target concentration of the third element larger than theinitial concentration of the third element; and depositing a film of thealloy of the first element, the second element, and the third element ona substrate according to the parameters of the PVD system.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A pair of physical vapor deposition (PVD) targetscomprising: a first PVD target containing a boron-containing cobalt ironalloy (FeCoB); and a second PVD target containing boron; and wherein thefirst PVD target and the second PVD target are used simultaneously in aPVD system for depositing a FeCoB film on a substrate.
 2. The pair ofPVD targets of claim 1, wherein the first PVD target contains the FeCoBwith an initial boron concentration, and the FeCoB film has a targetboron concentration larger than the initial boron concentration.
 3. Thepair of PVD targets of claim 1, wherein the first PVD target and thesecond PVD target are both exposed during deposition of the FeCoB film.4. The pair of PVD targets of claim 1, wherein the first PVD target andthe second PVD target are placed in a first recess and a second recess,respectively, in a lid of the PVD system.
 5. The pair of PVD targets ofclaim 2, wherein the initial boron concentration is 20%, and the targetboron concentration is 40%.
 6. The pair of PVD targets of claim 2,wherein the initial boron concentration is 20%, and the target boronconcentration is 30%.
 7. A physical vapor deposition (PVD) system,comprising: a first PVD target and a second PVD target, the first PVDtarget containing a boron-containing cobalt iron alloy (FeCoB) with aninitial boron concentration, and the second PVD target containing boron;and wherein parameters of the PVD system are determined based on atarget boron concentration larger than the initial boron concentration,and wherein a FeCoB film is deposited on a substrate according to theparameters of the PVD system.
 8. The PVD system of claim 7, wherein theparameters of the PVD system includes at least one of: voltages appliedto the first PVD target and the second PVD target; a depositionduration; and a concentration of a plasma-forming gas.
 9. The PVD systemof claim 7, wherein a boron concentration of the FeCoB film ismonitored.
 10. The PVD system of claim 9, wherein the monitoring is byusing X-ray photoelectron spectroscopy (XPS).
 11. The PVD system ofclaim 9, wherein a difference between the boron concentration of theFeCoB film and the target boron concentration is determined to be equalto or greater than a threshold, and wherein the parameters of the PVDsystem is adjusted based on the difference.
 12. The PVD system of claim7, wherein the first PVD target and the second PVD target are placed ina first recess and a second recess, respectively, in a lid of the PVDsystem.
 13. A physical vapor deposition (PVD) system, comprising: achamber body; a substrate support disposed in the chamber body andconfigured to support a substrate; a first PVD target containing aboron-containing cobalt iron alloy (FeCoB) with an initial boronconcentration; and a second PVD target containing boron; and whereinparameters of the PVD system are determined based on a target boronconcentration larger than the initial boron concentration, and wherein aFeCoB film is deposited on a substrate according to the parameters ofthe PVD system.
 14. The PVD system of claim 13, further comprising: alid comprising a first recess and a second recess, wherein the first PVDtarget and the second PVD target are placed in the first recess and thesecond recess, respectively.
 15. The PVD system of claim 14, furthercomprising: a first shutter corresponding to the first recess; and asecond shutter corresponding to the second recess; and wherein the firstshutter and the second shutter are controlled to cover or expose thefirst PVD target and the second PVD target.
 16. The PVD system of claimof 15, wherein the lid further comprises: a third recess configured toaccommodate a third PVD target; and a third shutter corresponding to thethird recess, wherein the third shutter is controlled to cover or exposethe third PVD target.
 17. The PVD system of claim 13, wherein theparameters of the PVD system includes at least one of: voltages appliedto the first PVD target and the second PVD target; a depositionduration; and a concentration of a plasma-forming gas.
 18. The PVDsystem of claim 13, wherein a boron concentration of the FeCoB film ismonitored.
 19. The PVD system of claim 18, wherein the boronconcentration of the FeCoB film is monitored by using X-rayphotoelectron spectroscopy (XPS).
 20. The PVD system of claim 18,wherein a difference between the boron concentration of the FeCoB filmand the target boron concentration is determined to be equal to orgreater than a threshold, and wherein the parameters of the PVD systemis adjusted based on the difference.